A small-sized sealed cover plate with a thin solder layer and its preparation method

Abstract

The present application discloses a small-sized sealed cover plate with a thin solder layer and a preparation method thereof. The method includes: using an automatic chip mounter to attach a mechanically punched cover plate to the adhesive surface of a sputtering process tape with a certain gap, and then attaching the adhesive surface of the single-sided sputtering process tape cut into a certain shape downward to the center of the cover plate; then evaporating a metal adhesion layer and a solder layer on a vacuum evaporation table; finally, using a laser to cut the evaporated layer along a reserved dividing line, heating and dissolving the sputtering process glue and the redundant evaporated layer to remove them, and obtaining the required small-sized sealed cover plate with a thin solder layer after cleaning and drying, which can avoid problems such as solder climbing on the thin cover plate and short circuits between the bonding wires and between the cover plate caused by the spherical solder formed by the melting of the thin package.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic packaging, and particularly relates to a small-sized sealed cover plate with a thin solder layer and a preparation method thereof. Background Art

[0002] High-reliability integrated circuits are usually sealed with gold-tin solder. For kovar cover plates with a size greater than 3 mm×3 mm and a thickness of 0.25 mm or more, a nickel-plated and gold-plated layer can be easily electroplated; in addition, with a width of 0.3 mm or more, 50 μm prefabricated gold-tin solder can be used for resistance spot welding to be fixed to the gold-plated kovar cover plate at four top corners.

[0003] With the need for miniaturization and thinning, the sizes of many cover plates are gradually less than 3 mm×3 mm, and the thickness of the cover plates is also less than 0.25 mm or even as thin as 0.05 mm. In this way, it is difficult to electroplate a gold-plated layer with a uniform thickness on the cover plate. In addition, if 50 μm prefabricated gold-tin solder is still used for resistance spot welding, solder climbing on the cover plate or even overhanging into the cavity to cause short circuit is likely to occur. At the same time, the width of the prefabricated gold-tin solder becomes narrower, and the gold-tin solder is prone to warping during spot welding. At this time, it is necessary to electroplate gold uniformly to control the gold-plating cost, and the thickness of the gold-tin solder needs to be reduced by 5 μm to 20 μm. While reducing the cost, the problems of solder climbing on the cover plate and short circuit caused by overhanging into the cavity are solved. In addition, with the reduction of the sealing width, there must be 100% gold-tin solder accumulation on the side surface of the cover plate after the hermetic seal cap is melted, so as to fully ensure the mechanical strength and reliability of the cover plate against impact and the like. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a small-sized sealed cover plate with a thin solder layer and a preparation method thereof.

[0005] In a first aspect, a small-sized sealed cover plate with a thin solder layer is provided, including: a cover plate, an adhesion layer, and a solder layer. The front sealing area and the side surface of the cover plate are sealed by an integral solder layer, and an adhesion layer is provided between the cover plate and the solder layer. Among them, the thickness of the cover plate is 0.05 - 0.25 mm, and the thickness of the solder layer is 5 μm - 20 μm.

[0006] Combined with the first aspect, in some embodiments of the first aspect, the adhesion layer includes titanium and / or nickel, and the thickness of the adhesion layer is 300 - 1000 angstroms; the solder layer includes gold and / or tin.

[0007] Combined with the first aspect, in some embodiments of the first aspect, the length of the cover plate is 0.500 - 3.00 mm, the width is 0.500 - 3.00 mm, and the cover plate has rounded corners, and the radius of the rounded corner is 0.005 - 0.010 mm.

[0008] In connection with the first aspect, in some embodiments of the first aspect, the cover plate comprises a low thermal expansion alloy.

[0009] In a second aspect, a method for preparing a small-sized sealed cover plate with a thin solder layer is provided, comprising: attaching the cover plate to a first sputtering process tape; attaching a second sputtering process tape to a side of the cover plate away from the first sputtering process tape, wherein the size of the second sputtering process tape is smaller than that of the cover plate; performing evaporation coating to form an adhesion layer, wherein the adhesion layer covers the first sputtering process tape, the cover plate, and the second sputtering process tape; performing evaporation coating to form a solder layer, the solder layer covering the adhesion layer; removing the first sputtering process tape, the second sputtering process tape, and the adhesion layer and the corresponding solder layer covering the parts of the first sputtering process tape and the second sputtering process tape to obtain the small-sized sealed cover plate with a thin solder layer.

[0010] In connection with the second aspect, in some embodiments of the second aspect, the thickness of the cover plate is 0.05 - 0.25 mm, the thickness of the solder layer is 5 - 20 μm, and the thickness of the adhesion layer is 300 - 1000 angstroms.

[0011] In connection with the second aspect, in some embodiments of the second aspect, the removing the first sputtering process tape, the second sputtering process tape, and the adhesion layer and the corresponding solder layer covering the parts of the first sputtering process tape and the second sputtering process tape to obtain the small-sized sealed cover plate with a thin solder layer comprises:

[0012] Cutting a groove along the edge of the second sputtering process tape on the solder layer on the cover plate, and cutting a groove along the edge of the solder layer on the side of the cover plate on the solder layer of the first sputtering process tape, wherein the depth of the groove is greater than the sum of the thicknesses of the solder layer and the adhesion layer; using a sol solution to dissolve the first sputtering process tape and the second sputtering process tape to obtain the small-sized sealed cover plate with a thin solder layer.

[0013] Specifically, the width of the groove is 0.05 mm, and the depth is 0.015 - 0.030 mm.

[0014] In connection with the second aspect, in some embodiments of the second aspect, the adhesion layer comprises titanium and / or nickel, and the solder layer comprises gold and / or tin.

[0015] In connection with the second aspect, in some embodiments of the second aspect, before attaching the cover plate to the first sputtering process tape, the preparation method further comprises: attaching the first sputtering process tape to an adhesive layer.

[0016] Compared with the prior art, the beneficial effect of the method of the present invention lies in:

[0017] (1) In the existing cover plates, there is no solder on the side. It is necessary to melt the solder in the sealing area and squeeze it out to accumulate on the side of the cover plate to form a meniscus welding surface that improves impact resistance. This is likely to cause appearance quality problems such as cover climbing and breakpoints in the weld due to poor wetting. In the cover plate of the embodiment of the present application, the side of the cover plate is provided with tin solder, and after melting, a meniscus solder morphology is directly formed on the side. Moreover, for a cover plate with a suitable thickness of 0.05 - 0.25 mm, the above problems can be avoided.

[0018] (2) The cover plate with AuSn solder in the present application is directly vapor-deposited, without the need for spot welding or cladding, reducing microvoids, oxidation impurities, etc. introduced by sunken solder joints and slight oxidation of cladding. It solves the problems of difficult position control of solder spot welding and cladding for cover plates smaller than 3 mm × 3 mm and low yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram of a small-size sealed cover plate with a thin solder layer provided by the present application.

[0020] Figure 2 It is a schematic mounting diagram of a small-size sealed cover plate with a thin solder layer provided by the present application.

[0021] Figure 3 It is a schematic diagram of vapor-depositing an adhesion layer on a small-size sealed cover plate with a thin solder layer provided by the present application.

[0022] Figure 4 It is a schematic diagram of vapor-depositing a solder layer on a small-size sealed cover plate with a thin solder layer provided by the present application.

[0023] Figure 5 It is a schematic diagram of laser cutting the vapor-deposited layer of a small-size sealed cover plate with a thin solder layer provided by the present application.

[0024] 1. Cover plate; 2. Adhesion layer; 3. Solder layer; 4. Bonding adhesive layer; 5. First sputtering process tape; 6. Groove; 7. Second sputtering process tape. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] In the production process of some small-size sealed cover plates with a thin solder layer, the thickness of the Au80Sn20 solder is uniform. When the prefabricated solder sheet melts, it first forms a ball and then wets and spreads, which is likely to cause solder climbing of the thin cover plate and short circuits between the ball solder melted in the thin package and the bonding wire and between the ball solder and the cover plate.

[0027] The present application provides a small-sized sealed cover plate with a thin solder layer and a preparation method thereof. An automatically placed mechanical punched cover plate is attached to the adhesive surface of a sputtering process tape with a certain gap by an automatic placement machine, and then the adhesive surface of the single-sided sputtering process tape cut into a certain shape is attached face-down in the center of the cover plate. Then, a metal adhesion layer and a solder layer are deposited by a vacuum evaporation platform. Finally, the deposited layer is cut along a reserved dividing line by a laser, and the sputtering process glue and the redundant deposited layer are removed by heating and dissolving the glue, and after cleaning and drying, the required small-sized sealed cover plate with a thin solder layer is obtained, which can avoid problems such as solder climbing on the thin cover plate and short circuits between the bonding wires and the cover plate easily caused by the melting of the thin package into spherical solder.

[0028] As Figure 1 shown, the present application provides a small-sized sealed cover plate with a thin solder layer, including: a cover plate 1, an adhesion layer 2, and a solder layer 3. The front sealing area and the side of the cover plate are sealed by an integral solder layer 3, and an adhesion layer 2 is provided between the cover plate 1 and the solder layer 3. Among them, the thickness of the cover plate 1 can be 0.05 - 0.25 mm, and the thickness of the solder layer 3 can be 5 μm - 20 μm.

[0029] In some embodiments, the cover plate can also serve as a substrate.

[0030] In some embodiments, the adhesion layer 2 can include titanium (Ti) and / or nickel (Ni), and the thickness of the adhesion layer 2 can be 300 - 1000 angstroms. Exemplarily, the adhesion layer 2 can be TiNi.

[0031] In some embodiments, the solder layer 3 includes gold (Au) and / or tin (Sn). Exemplarily, the solder layer 3 can be Au80Sn20.

[0032] In some embodiments, the length of the cover plate 1 can be 0.500 - 3.00 mm, the width can be 0.500 - 3.00 mm, and the cover plate has rounded corners, and the radius of the chamfered circle can be 0.005 - 0.010 mm. Specifically, the cover plate 1 can include a low thermal expansion alloy. Exemplarily, the cover plate 1 can be 4J42 alloy.

[0033] As Figures 2 to 5 shown, the present application also provides a preparation method for a small-sized sealed cover plate with a thin solder layer, including:

[0034] S100, attaching the cover plate 1 to the first sputtering process tape 5;

[0035] S200, attaching the second sputtering process tape 7 to the side of the cover plate 1 away from the first sputtering process tape 5, where the size of the second sputtering process tape 7 is smaller than that of the cover plate 1;

[0036] S300, perform evaporation coating to form an adhesion layer 2, wherein the adhesion layer 2 covers the first sputtering process tape 5, the cover plate 1, and the second sputtering process tape 7;

[0037] S400, perform evaporation coating to form a solder layer 3, the solder layer 3 covering the adhesion layer 2;

[0038] S500, remove the first sputtering process tape 5, the second sputtering process tape 7, and the adhesion layer and the corresponding solder layer covering the second sputtering process tape portion and the second sputtering process tape portion to obtain the small-sized sealed cover plate with a thin solder layer.

[0039] Specifically, the thickness of the cover plate 1 can be 0.05 - 0.25 mm. Among them, the large metal plate is first precision machined to produce the cover plate 1 with the designed size and shape, and the cover plate 1 can have rounded corners.

[0040] Before step S100, the first sputtering process tape 5 can also be attached to the adhesive layer 4. In step S100, specifically, an automatic pick-and-place machine can be used to attach the cover plate 1 that has been cleaned and visually inspected to the sputtering process tape with a frame at a certain gap, arranged in a full array. Exemplarily, this gap can be 0.05 - 0.50 mm.

[0041] In step S200, specifically, a single-sided tape cut into a certain shape, that is, a preformed single-sided sputtering process tape, which is the second sputtering process tape 7, can be attached to the center of the cover plate 1, with the adhesive side facing down the cover plate 1. The adhesive side adheres to the cover plate, and the area of the cover plate 1 not covered by the tape is the solder evaporation coating area. Step S200 obtains the Figure 2 mounting schematic diagram of the small-sized sealed cover plate with a thin solder layer as shown.

[0042] In step S300, specifically, the frame can be sent into a vacuum evaporation chamber. The thickness of the adhesion layer 2 can be 300 - 1000 Å. The evaporation coating of the adhesion layer on the small-sized sealed cover plate with a thin solder layer obtained in step S300 is as Figure 3 shown.

[0043] In some embodiments, in step S400, the solder layer 3 can be Au80Sn20, and the thickness of the solder layer 3 can be 5 μm - 20 μm. In this step, finally, Au with a thickness of 500 - 1000 Å can also be evaporated on the surface. Figure 4 It is a schematic diagram of evaporation coating the solder layer on a small-sized sealed cover plate with a thin solder layer obtained in step 400. Among them, both the solder layer 3 and the adhesion layer 2 belong to the evaporation coating layer.

[0044] In some embodiments, the specific sealed design dimensions can be determined according to the cover plate thickness, the flatness of the outer shell sealed area, and the sealing width, etc.

[0045] In some embodiments, in step S500, removing the first sputtering process tape 5, the second sputtering process tape 7, and the adhesion layer 2 and the corresponding solder layer 3 covering the portions of the first sputtering process tape 7 and the second sputtering process tape 7 to obtain the small-sized sealed cover plate with a thin solder layer may specifically include: cutting a groove 6 along the edge of the second sputtering process tape 7 on the solder layer 3 on the cover plate 1, and cutting a groove 6 along the edge of the solder layer on the side surface of the cover plate 1 on the solder layer 3 of the first sputtering process tape 5, wherein the depth of the groove 6 is greater than the sum of the thicknesses of the solder layer 3 and the adhesion layer 2; using a sol solution to dissolve the first sputtering process tape 5 and the second sputtering process tape 7 to obtain the small-sized sealed cover plate with a thin solder layer.

[0046] Exemplarily, after taking it out from the vacuum evaporation stage, the evaporation coating layer can be cut along the reserved dividing line by using ultraviolet picosecond / femtosecond laser. Specifically, the width of the groove 6 can be 0.05 mm, and the depth can be 0.015 mm to 0.030 mm. As Figure 5 shown, it is a schematic diagram of laser cutting of the evaporation coating layer of the small-sized sealed cover plate with a thin solder layer according to an embodiment of the present application.

[0047] Finally, after heating the sol to remove the excess evaporation coating layer, removing the adhesive layer and the support film, and performing ultra-clean cleaning and drying, the small-sized sealed cover plate with a thin solder layer as Figure 1 shown is obtained.

[0048] The following is described in conjunction with specific embodiments.

[0049] Embodiment 1:

[0050] Clad about 12 μm of Au80Sn20 solder, the width of the solder is 0.15 mm, and the cover plate is a 4J42 alloy with dimensions of 1.20 mm × 1.20 mm × 0.15 mm (thickness). Specifically as follows:

[0051] First, use a precision stamping die to stamp a 4J42 alloy cover plate with dimensions of 1.20 mm × 1.20 mm × 0.15 mm (thickness), the fillet radius of the 4 corners is 0.10 mm, and use vibratory grinding to remove burrs, and make the radius of the side of the cover plate be 0.01 mm to 0.03 mm, and perform cleaning and drying such as degreasing and deoxidation;

[0052] Next, use the Datacon 2200evo automatic chip mounter to attach a cover plate with dimensions of 1.20 mm × 1.20 mm × 0.15 mm to the 50-μm-thick adhesive layer 4 of the sputtering process tape SP-UV-RT-230TV-158-50T on an 8-inch stainless-steel frame with a 0.15-mm gap, filling the entire 8 inches; then attach the SP-UV-RT-230TV-158-50T sputtering process tape cut into a single-sided tape of 0.88 mm × 0.88 mm to the center of the cover plate with the adhesive side facing the cover plate;

[0053] Place the 8-inch stainless-steel frame and its cover plate, etc. on the 8-inch planetary disk of the ei-5z vacuum evaporation platform, evacuate to 4×10 -4 Pa and then clean with an electron gun. Next, evaporate layers of 300 Å Ti, 300 Å Ni, a 12-μm Au80Sn20 layer, and a 500-Å Au layer;

[0054] Finally, use a 355-nm picosecond laser machine to cut a groove with a width of 0.05 mm and a depth of 0.015 mm to 0.030 mm along the edge of the 0.88 mm × 0.88 mm tape on the cover plate. Then, put the 8-inch stainless-steel frame and the things on it into a sol solution at 30 to 50 °C. The adhesive layer and the support film dissolve, and the excess evaporated coating and the cover plate fall off and sink to the bottom. Use a magnet to extract the cover plate that has sunk to the bottom and perform ultra-clean cleaning and hot air drying at 60 to 80 °C.

[0055] It should be noted that in this article, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or elements inherent to such a process, method, article or device.

[0056] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A sealing cover plate, characterized in that: include: Cover, adhesive layer, and solder layer, The front sealing area and the side of the cover plate are sealed by an integral solder layer, and an adhesive layer is provided between the cover plate and the solder layer. The thickness of the cover plate is 0.05 to 0.25 mm, and the thickness of the solder layer is 5 μm to 20 μm; The cover plate is prepared by the following method: attaching the cover plate to the first sputtering process tape; Attaching a second sputtering tape to a side of the cover plate away from the first sputtering tape, wherein the second sputtering tape is smaller than the cover plate; Vapor deposition to form an adhesive layer, wherein the adhesive layer covers the first sputtering tape, the cover plate, and the second sputtering tape; Vapor deposition to form a solder layer, wherein the solder layer covers the adhesion layer; The first sputtering tape, the second sputtering tape, and the adhesive layer and the corresponding solder layer covering the first sputtering tape portion and the second sputtering tape portion are removed to obtain the sealing cover plate.

2. The sealing cover plate according to claim 1, characterized in that: The adhesion layer includes titanium and / or nickel, and the thickness of the adhesion layer is 300 to 1000 angstroms; The solder layer includes gold and / or tin.

3. The sealing cover plate according to claim 1 or 2, characterized in that: The cover plate is 0.500-3.00 mm long and 0.500-3.00 mm wide. Furthermore, the cover plate has rounded corners, and the radius of the rounded corners is 0.005-0.010 mm.

4. The sealing cover plate according to claim 1 or 2, characterized in that: The cover plate includes a low thermal expansion alloy.

5. A method for preparing a sealing cover plate, characterized in that: include: attaching the cover plate to the first sputtering process tape; Attaching a second sputtering tape to a side of the cover plate away from the first sputtering tape, wherein the second sputtering tape is smaller than the cover plate; Vapor deposition to form an adhesive layer, wherein the adhesive layer covers the first sputtering tape, the cover plate, and the second sputtering tape; Vapor deposition to form a solder layer, wherein the solder layer covers the adhesion layer; The first sputtering tape, the second sputtering tape, and the adhesive layer and the corresponding solder layer covering the first sputtering tape portion and the second sputtering tape portion are removed to obtain the sealing cover plate.

6. The preparation method according to claim 5, characterized in that: The thickness of the cover plate is 0.05-0.25 mm, the thickness of the solder layer is 5 μm-20 μm, and the thickness of the adhesion layer is 300-1000 angstroms.

7. The preparation method according to claim 5 or 6, characterized in that: The step of removing the first sputtering tape, the second sputtering tape, and the adhesive layer and the corresponding solder layer covering the second sputtering tape portion and the second sputtering tape portion to obtain the sealing cover plate comprises: Cutting a groove on the solder layer on the cover plate along the edge of the second sputtering tape, and cutting a groove on the solder layer of the first sputtering tape along the edge of the solder layer on the side of the cover plate, wherein the depth of the groove is greater than the sum of the thicknesses of the solder layer and the adhesive layer; The first sputtering process tape and the second sputtering process tape are dissolved by using a sol solution to obtain the sealing cover plate.

8. The preparation method according to claim 7, characterized in that: The groove has a width of 0.05 mm and a depth of 0.015 mm to 0.030 mm.

9. The preparation method according to claim 5 or 6, characterized in that: The adhesion layer includes titanium and / or nickel, and the solder layer includes gold and / or tin.

10. The preparation method according to claim 5 or 6, characterized in that: Before attaching the cover plate to the first sputtering process tape, the preparation method further includes: The first sputtering process tape is attached to the adhesive layer.

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